Comparative morphology of the cottid genus Myoxocephalus based on meristic, morphometric, and other anatomical characters

• Published in: Canadian Journal of Zoology
• Main Author: Cowan, Garry I. McT.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1971
• Subjects: Bering Sea; Alaska
• Online Access: http://dx.doi.org/10.1139/z71-217; http://www.nrcresearchpress.com/doi/pdf/10.1139/z71-217

Specimens representing 15 nominal species of the genus Myoxocephalus were subjected to detailed comparative morphological study to determine some of the more important species characteristics and also those indicating potential for expressing phylogenetic progression.Analysis of seven meristic characters revealed that none of them is consistently sexually dependent. Geographic variation within the species indicated the presence of both latitudinal and longitudinal clines. No evolutionary group affinities were evident.The morphology of the cephalic lateral line system, lateral line ossicles, squamation, and olfactory rosettes were found to exhibit a high degree of specificity, especially the first three systems. With the exception of the lateral line ossicles all evidenced some potential as indicators of phylogeny.Analysis of 23 morphometric characters was accomplished by cluster analysis. The resultant clusters indicated heterogenous unnatural groupings.On the basis of these analyses well-defined species differences exist in most of the major morphological features. The nominal species M. scorpius (Linnaeus) includes three distinct species (Gulf of Alaska, Arctic–East coast, and European). In addition, the data indicate that the genus is probably composed of three basic evolutionary lines: the Holarctic–Atlantic, Bering Sea–Transpacific, and Asiatic.